1. Field of the Invention
The invention relates to a spot filmer for a diagnostic X-ray machine and more particularly to a spot filmer which can be front or back loaded with either a standard 91/2 inch square or 14 inch square film cassette. The invention also encompasses a precision drive for a pair of divided cassette half trays or frames and an orthogonal axis guide and transport system for the frames.
2. Description of the Prior Art
Spot filmers for diagnostic X-ray machines are well known including pneumatically driven and electric motor driven types. Most domestic spot filmers are constructed to accept a standard 91/2 inch square cassette, and the cassette is generally loaded at the front of the spot filmer, sometimes called "side loading". Older domestic devices employed back loading, sometimes called "top loading", prior to about 1958 when front loading was introduced. Certain new domestic designs have reintroduced back loading in combination with front loading for the operator's convenience, although limited to use of the 91/2 inch square cassette.
Film cassettes of various sizes can be accommodated by some European devices, while a few domestic models can handle the 14 inch square standard cassette as well as the 91/2 inch square cassette with front loading only. In general, the European devices which can accommodate various cassette sizes employ complex and costly tray size adjustment mechanisms. No domestic or foreign spot film devices are known which allow both front and back loading of 91/2 and 14 inch square cassettes. It is the main objective of the invention to provide such a spot filmer of increased utility and convenience of use, and to also provide a simple and reliable precision drive system for the spot filmer embodying the invention which is economically practical, sturdy and durable.